TWI472220B - Light quantity measuring apparatus - Google Patents

Description

Light measuring device

The present invention relates to a light amount measuring device capable of measuring a light to be measured whose amount of light periodically changes.

The light amount measuring device that measures the amount of light to be measured is generally provided with a sensor that outputs a signal corresponding to the amount of light of the light to be received, and specifies the light to be measured from the output of the sensor. The amount of light. However, in such a light amount measuring device, if it is desired to measure the light to be measured which periodically changes in the amount of light emitted by the display, the measurement result may vary depending on the timing of the measurement. The problem of stable measurement results cannot be obtained.

In order to solve such a problem, as shown in the "VESA Flat Panel Display Standard" (US), p. 172, it is generally performed by comparing with the light to be measured. The low-pass filter having a sufficiently long time constant is used to filter the output of the sensor so that the measurement result is not affected by the periodic variation of the amount of light to be measured.

Further, by using a period of time sufficiently longer than the fluctuation period of the amount of light of the light to be measured, the charge generated by the sensor is accumulated, so that the measurement result does not receive the amount of light of the light to be measured. The impact of cyclical changes.

Further, as shown in Japanese Patent Laid-Open Publication No. 2003-18458, the measurement is performed by accumulating the electric charge generated by the sensor by using an integral multiple of the fluctuation period of the light amount of the light to be measured. As a result, it is not affected by the periodic variation of the amount of light to be measured.

Further, the measurement of the amount of light to be measured is repeated, and the average of the measurement results is obtained, whereby the measurement result is not affected by the periodic variation of the amount of light to be measured.

However, in the method of filtering the output of the sensor by the low-pass filter, when it is necessary to measure the measured light whose cycle of variation is different, it is necessary to prepare a time constant of A plurality of different low-pass filters are selected, and the low-pass filter to be used is selected in accordance with the fluctuation period of the amount of light to be measured. However, the selection of the low-pass filter is complicated, and when the period of fluctuation of the amount of light to be measured is not stable or the period of variation of the amount of light of the measured light is unknown, the low-pass filter is used. Choosing a system becomes difficult. Therefore, the output of the sensor is filtered by a low-pass filter having a very long time constant, and the time required for the measurement becomes very long.

Further, in the method of accumulating the charge generated by the sensor for a sufficiently long period of time compared to the fluctuation period of the amount of light to be measured, the time required for the measurement is extremely long. Further, when a sensor having a high sensitivity which is generalized in recent years is used, during the period in which the electric charge is accumulated, the saturation of the electric charge is caused, and the measurement cannot be performed appropriately.

Further, in the method of accumulating the electric charge generated by the sensor using an integral multiple of the fluctuation period of the light amount of the light to be measured, when the fluctuation period of the light amount of the light to be measured is not stable, or When the fluctuation period of the amount of light to be measured is unknown, the accumulation of electric charge cannot be synchronized with the periodic operation of the amount of light to be measured, and the measurement cannot be performed appropriately. In addition, when a sensor having a high sensitivity that is generalized in recent years is used, during the period in which the electric charge is accumulated, the saturation of the electric charge is caused, and the measurement cannot be performed appropriately.

In addition, in the method of repeatedly measuring the amount of light of the light to be measured and taking the average of the measurement results, in order to prevent the measurement result from being affected by the fluctuation of the amount of light to be measured between the measurement and the measurement, It takes a lot of measurements, and the time required for the measurement is very long. In addition, if it is intended to measure the amount of light of the light to be measured which is equal to or less than the number of light-emitting periods of a light emitted by a CRT (Cathode Ray Tube) display or a plasma display, the measurement and measurement may be performed. The period between them becomes a light-emitting period and a large error occurs in the measurement result. Such a large error may occur in the case of measuring the amount of light emitted by a liquid crystal display using a black insertion general driving method.

In addition, the problem of charge saturation can be eliminated by reducing the light to be measured at the sensor by the dimming filter. However, if the transmittance of the dimming filter is low, the transmittance is ensured. The accuracy is difficult, and depending on the amount of light to be measured, there is also a problem that if the dimming filter is used, the repeatability cannot be ensured, and if the dimming filter is not used, the measurement is in progress. The time required is very long.

The present invention has been made in order to solve such problems, and an object of the invention is to provide a light amount measuring device capable of measuring a light to be measured whose amount of light periodically changes in a short time.

In order to solve the problem, the invention of claim 1 is a light amount measuring device which is a light amount measuring device that measures the amount of light to be measured, and is characterized in that: a charge generating means is provided to generate a light-receiving means And a charge means for accumulating the charge generated by the charge generation means; and the A/D conversion means converting the amount of charge accumulated in the accumulation means into a digital value And accumulating means for accumulating the plurality of digit values; and controlling means for controlling the light quantity measuring means, and controlling by the aforementioned control means, the charge generating means is continuously generated during the measuring period In the storage period of the light amount of the light to be measured, the charge means generates the charge generated by the charge generation means, and the A/D is accumulated in each of the plurality of accumulation periods in which the measurement period is divided. The conversion means converts the amount of electric charge accumulated in the accumulation means in each of the plurality of accumulation periods, into a digital value, The adding means accumulates the digital values of the complex numbers converted by the A/D conversion means.

According to the invention, in the light quantity measuring device according to the first aspect of the invention, the apparatus for adjusting the amount of light to be measured, which is prepared in advance before the start of the measurement period, is The amount of light of the light to be measured that reaches the aforementioned charge generating means is adjusted.

The invention of claim 3, wherein the control means is based on a pre-measurement before the start of the measurement period, in the light quantity measuring device according to the application item 1 or the application item 2. The amount of light is measured to determine the length of the accumulation period.

The light quantity measuring device according to any one of the preceding claims, wherein the control means is determined based on a fluctuation period of the amount of light to be measured. The length of the savings period.

The invention of claim 5, further comprising: a first receiving means for receiving an input of a fluctuation period of the amount of light to be measured, wherein the control means is based on the foregoing The length of the accumulation period is determined by the fluctuation period of the input received by the first receiving means.

The light quantity measuring device according to the fourth aspect of the invention, further comprising: obtaining means for obtaining a signal that changes in synchronization with a change in the amount of light to be measured, wherein the control means is The signal obtained by the acquisition means detects the fluctuation period of the amount of light to be measured, and determines the length of the accumulation period based on the detected fluctuation period.

The invention according to claim 1, further comprising: a second receiving means for receiving an input of a length of the measurement period, wherein the control means is based on a length of the accumulation period The length of the measurement time input by the second receiving means is determined to determine the number of divisions during the measurement period.

According to the present invention, the saturation of the accumulation means is not generated, and the light to be measured whose amount of light periodically changes can be appropriately measured in a short time.

According to the invention of the application item 2, the range of the amount of light that can be measured can be increased.

According to the invention of claim 3, since the saturation of the accumulation means is more difficult to occur, the measurement light can be measured more appropriately.

According to the invention of the application item 4 or the application item 6, the measurement accuracy of the light amount can be improved.

According to the invention of claim 7, the measurement time can be kept constant.

<1 First Embodiment>

<1-1 Composition of Spectroradiometer 1]

Fig. 1 is a schematic view showing a spectroradiometer 1 according to a first embodiment of the present invention. The spectroradiometer 1 mainly measures the spectral radiance of the light to be measured 604 by using the light emitted from the display 602 such as a CRT display, a plasma display, or a liquid crystal display as the light to be measured 604.

As shown in FIG. 1 , the spectroradiometer 1 is provided with an optical system 102, a dimming filter 104, a shutter 106, a dispersing element 108, a sensor 110, an A/D converter 112, and a communication interface. 114. The display unit 116, the operation unit 118, the synchronization signal input terminal 120, and the control calculation unit 122.

The optical system 102 guides the light to be measured 604 incident on the spectroradiometer 1 to the sensor 110 via the dispersing element 108, and forms an optical image on the light receiving surface of the sensor 110. The optical system 102 can be constructed by combining a lens or a mirror.

The dimming filter 104 dims the transmitted light. The dimming filter 104 is controlled by the control calculation unit 122, and is inserted and removed in the optical path of the light to be measured 604. When the dimming filter 104 is inserted in the optical path of the light to be measured 604, the light incident on the spectroradiometer 1 is dimmed via the dimming filter 104, and then reaches the sensor. 110 places. On the other hand, when the dimming filter 104 is removed from the optical path of the light to be measured 604, the light incident on the spectroradiometer 1 reaches the sensor 110 without being dimmed. Therefore, the dimming filter 104 is controlled by the control calculation unit 122 and functions as an adjustment means for adjusting the amount of light of the light to be measured 604 at the sensor 110. The transmittance of the dimming filter 104 is preferably 2% or more, and more preferably 5% or more. This is because if the transmittance is within this range, the dimming filter 104 having a good transmittance accuracy can be used.

The shutter 106 shields the light. The shutter 106 is controlled by the control calculation unit 122 and is inserted and removed in the optical path of the light to be measured 604. When the shutter 106 is inserted into the optical path of the light to be measured 604, the light to be measured 604 incident on the spectroradiometer 1 does not reach the sensor 110. On the other hand, when the shutter 106 is removed from the optical path of the light to be measured 604, the light to be measured 604 incident on the spectroradiometer 1 is reached at the sensor 110.

The dispersing element 108 distributes the incident light 604 to be measured at each wavelength. As the dispersing element 108, for example, a diffraction grating or a crucible can be used. Among them, as the dispersing element 108, it is preferable to use a concave diffraction grating. This is because if the concave diffraction grating is used as the dispersion element 108, the optical system 102 can be simplified.

The sensor 110 is a light to be measured 604 that is dispersed at each wavelength by the light passing through the dispersing element 108, and outputs a signal representing the amount of light of the light to be measured 604 in each wavelength component.

FIG. 2 is a schematic diagram of the sensor 110. 2 is a plan view of the sensor 110. As shown in FIG. 2, in general, a plurality of photodiodes 128 are arranged at the light receiving surface 126 of the sensor 110. The arrangement direction of the photodiodes 128 coincides with the direction in which the dispersion elements 108 are dispersed by the measurement light 604 at each wavelength. Therefore, each of the photodiodes 128 photoelectrically converts a specific wavelength component of the light to be measured 604, and generates an electric charge corresponding to the amount of light of a specific wavelength component of the light 604 to be received. The charge is saved. Further, it is not necessary to carry out the generation and accumulation of electric charges by the photodiode 128, and it is also possible to provide the photodiode at the charge accumulating portion provided separately from the photodiode 128. The charge generated by the body 128 is accumulated.

The sensor 110 is provided with a CCD (Charge Coupled Device) 130 and an FD (Floating Diffusion) amplifier 132. The CCD 130 transmits the electric charge generated and accumulated by the photodiode 128 to the FD amplifier 132. The FD amplifier 132 is provided with an analog pixel signal having an amount corresponding to the amount of charge transferred by the CCD 130. Further, instead of the FD amplifier 132, an FG (Floating Gate) amplifier may be used.

If it is returned to FIG. 1 and described, the A/D converter 112 converts the analog pixel signal output by the sensor 110 into digital pixel data, and outputs it to the control calculation unit 122. Thereby, the A/D converter 112 can convert the amount of electric charge accumulated in the photodiode 128 into a digital value and output it.

The communication interface 114 connects the spectroradiometer 1 to an external device such as an external computer.

The display unit 116 displays the measurement result of the spectroradiometer 1 . Further, instead of displaying the measurement result by the display unit 116 or displaying the measurement result on the display unit 116, the measurement result may be output to an external device connected to the spectroradiometer 1 via the communication interface 114. At the office.

The operation unit 118 accepts an operator's operation such as input of a fluctuation period of the amount of light to be measured or a length of the measurement period (hereinafter referred to as "measurement time"). In addition, instead of accepting the operation of the operator by the operation unit 118, or accepting the operation of the operator by the operation unit 118, it is also acceptable to be connected to the outside of the spectroradiometer 1 via the communication interface 114. Remote operation from the machine.

The synchronizing signal input terminal 120 obtains a signal in which a vertical synchronizing signal generally changes in accordance with a change in the amount of light of the light to be measured 604 as in the case of measuring light emitted from the CRT display.

The control calculation unit 122 is an embedded computer including at least a CPU 136 and a memory 138, and causes the CPU 136 to execute a control program read from the memory 138 to sense the dimming filter 104 and the shutter 106. The detector 110, the A/D converter 112, the communication interface 114, the display unit 116, the operation unit 118, or other components of the spectroradiometer 1 are controlled. Further, the control calculation unit 122 calculates the spectral radiance from the set of pixel data acquired from the A/D converter 112 by causing the CPU 136 to execute the control program read from the memory 138.

The control calculation unit 122 transmits the charge generated and accumulated by the photodiode 128 from the photodiode 128 to the FD amplifier in the middle of the measurement period in which the photodiode 128 photoelectrically converts the measurement light 604. At 132, and in the FD amplifier 132, an analog signal pixel having a voltage corresponding to the amount of charge transferred by the CCD 130 is output, and in the A/D converter 112, the sensor is used. The analog pixel signal of the output of 110 is converted into digital pixel data.

As a result, the electric charge generated and accumulated in the measurement period of the photodiode 128 is read and divided into a plurality of times, and the control unit 122 obtains the measurement period MP as shown in FIG. In the subsequent accumulation periods SP(1), SP(2), ..., SP(M), the amount of charge Q(1, i), Q generated by the photodiode 128 and accumulated is reflected in each of the SP(1), SP(2), ..., SP(M). 2, i), ..., Q(M, i) (i = 1, 2, ..., N) pixel data D (1, i), D (2, i), ..., D (M, i). Here, the pixel data D(j, i) is generated and accumulated in response to the first photodiode 128 in the accumulation period SP(j) (j=1, 2, ..., M). The pixel signal A(j, i) of the voltage of the amount of charge Q(j, i) is converted into a digital value.

Further, the control calculation unit 122 converts the plural pixel data D(1, i), D(2, i), . . . D(M, i) is accumulated according to Equation 1, and the amount of charge Q(1), Q(2), which is generated and accumulated by the photodiode 128 during the measurement period MP is calculated. . . , Q (N) pixel data D (1), D (2),. . . D(N).

Then, the control calculation unit 122 is based on the pixel data D(1), D(2), . . . D(N) is used to calculate the spectral radiance.

<1-2 Action of Spectroradiometer 1

4 and 5 are flowcharts for explaining the operation of the spectroradiometer 1 by the control by the control unit 122.

In the measurement of the spectral radiance, first, as shown in FIG. 4, the control calculation unit 122 controls the sensor 110 and the A/D conversion unit 112, and performs preliminary measurement on the amount of light to be measured 604 ( Step S101). The amount of light of the light to be measured 604 can be calculated by the pixel data acquired by the control calculation unit 122 and the transmittance of the dimming filter 104 in a state where the light-reducing filter 104 is inserted into the optical path of the light to be measured 604. When the dimming filter 104 is removed from the optical path of the light to be measured 604, the pixel data obtained by the control unit 122 can be calculated. Here, since it is not necessary to improve the accuracy of the preliminary measurement, it is also possible to allow the preliminary measurement to be performed in a shorter time than the official measurement. It is not necessary to perform the preliminary measurement using the sensor 110, and a sensor for preliminary measurement different from the sensor 110 may be provided, and the preliminary measurement may be performed using a sensor for preliminary measurement.

Next, the control calculation unit 122 determines the lengths of the accumulation periods SP(1), SP(2), ..., SP(M) (hereinafter referred to as "storage time") (step S102). The control calculation unit 122 determines the accumulation period in which the photodiode 128 is not saturated, based on the amount of light to be measured 604 measured in step S101. As a result, irrespective of the measurement time or the amount of light of the light to be measured 604, it is difficult to generate saturation of the photodiode 128, and the amount of light to be measured 604 can be appropriately measured.

In addition, it is expected that the control calculation unit 122 makes the measurement time the light to be measured 604 based on the fluctuation period of the light amount of the light to be measured 604 that is received by the operation unit 118 in a range in which the photodiode 128 is not saturated. The accumulation time is determined in such a manner that the fluctuation period of the light amount is an integral multiple. Further, it is also expected that the control calculation unit 122 detects the fluctuation period of the amount of light of the light to be measured 604 from the signal acquired by the synchronization signal input terminal 120, and detects the range in which the photodiode 128 does not saturate. The fluctuation period is determined such that the measurement time is an integral multiple of the fluctuation period of the light amount of the light to be measured 604. In this case, if the accumulation period is determined based on the fluctuation period of the amount of light of the light to be measured 604, the measurement accuracy of the amount of light to be measured 604 can be improved.

In addition, the accumulation time may be the same for all of the accumulation periods SP(1), SP(2), ..., SP(M), or the accumulation periods SP(1), SP(2), ..., Each of SP(M) becomes different.

Next, the control calculation unit 122 inserts and removes the dimming filter 104 based on the amount of light of the light to be measured 604 that has been measured (step S103). In other words, when the amount of light of the light to be measured 604 that is to be measured in a state where the light-reducing filter 104 is inserted into the optical path of the light to be measured 604 is equal to or less than the threshold value TH1, the light to be measured 604 is The light-reducing filter 104 is removed by the optical path, and the light quantity of the light to be measured 604 which is prepared and measured in a state where the light-reducing filter 104 is removed from the optical path of the light to be measured 604 is compared with the threshold value TH2. Larger, the dimming filter 104 is inserted into the optical path of the light 604 to be measured. In this manner, the amount of light to be measured at the photodiode 128 is adjusted based on the amount of light to be measured 604, and when the amount of light to be measured 604 is large, the light to be measured is first measured. The 604 is dimmed and then guided to the sensor 110. When the amount of light to be measured 604 is small, the measured light 604 is not dimmed to the sensor 110. Thus, the range of the amount of light that can be measured in the formal measurement can be increased.

Moreover, although the threshold TH1 of the de-wiffering filter 104 and the threshold TH2 of the insertion dimming filter 104 may be set to be the same, by removing the threshold of the dimming filter 104. The TH1 is different from the threshold value TH2 of the insertion dimming filter 104 by hysteresis control, and it is possible to prevent the dimming filter from being frequently inserted and removed, and the measurement result is deviated.

When the preliminary measurement is completed, the spectroradiometer 1 starts the formal measurement, and after the sampling measurement in steps S104 to S112, the dark measurement in steps S113 to S121 is continued.

In the sampling measurement, first, as shown in FIG. 4, the control calculation unit 122 controls the shutter 106 and turns on the shutter 106 (step S104), and controls the sensor 110 to start the photodiode. The accumulation of charge of 128 (step S105).

Next, the control calculation unit 122 waits for the accumulation time to elapse (step S106), and after the accumulation time has elapsed, controls the sensor 110 and transfers the charge generated and accumulated by the photodiode 128 in the CCD 130 to the FD. At the amplifier 132 (step S107), the FD amplifier 132 is caused to output a pixel signal (step S108).

Next, the control calculation unit 122 converts the analog pixel signal into digital pixel data in the A/D conversion unit 112 (step S109), and stores the acquired pixel data in the memory 138 (step S110). ).

Next, the control calculation unit 122 accumulates the pixel data stored in the memory 138 in accordance with Equation 1 (step S111), and when the measurement time has elapsed ("YES" in step S112), the process ends. The sampling measurement is started and the dark measurement is started, and when the measurement time has not elapsed ("NO" in step S112), the process returns to step S106, and waits for the passage of the next accumulation period.

Here, between the charge transfer (step S107), the pixel signal output (step S108), the A/D conversion (step S109), and the pixel data memory (step S110), the photodiode 128 continues without interruption. The generation and accumulation of electric charge. Therefore, the photodiode 128 continuously photoelectrically converts the light to be measured 604 between the measurement periods MP, and continues to generate an electric charge corresponding to the amount of light of the light to be measured 604 of the received light, and at the same time, during the accumulation period SP ( 1) The charge generated in each of SP(2), ..., SP(M) is accumulated. Further, the A/D conversion unit 112 is the amount Q (1, i) of the electric charge accumulated in the photodiode 128 in each of the accumulation periods SP(1), SP(2), ..., SP(M). ), Q(2, i), ..., Q(M, i) are transformed into pixel data D(1, i), D(2, i), ... D(M, i). Further, the control calculation unit 122 accumulates the complex pixel data D(1, i), D(2, i), ..., D(M, i) converted by the A/D converter 112, and calculates The pixel data D(i) covering the entirety of the measurement period MP is shown.

In the dark measurement, first, as shown in FIG. 5, the control calculation unit 122 controls the shutter 106 and closes the shutter 106 (step S113), and controls the sensor 110 to start the photodiode. The accumulation of charge of 128 (step S114).

Next, in the same manner as S106 to S111 of the sampling measurement, the waiting accumulation time elapse (step S115), charge transfer (step S116), pixel signal output (step S117), A/D conversion (step S118), and pixel data are performed. The memory (step S119) and the pixel data accumulation (step S120), when the measurement time has elapsed ("YES" in step S121), the dark measurement is ended, and when the measurement time has not elapsed ("NO in step S121" "), then return to step S115 and wait for the passage of the next accumulation period.

After the dark measurement is completed, the control calculation unit 122 subtracts the pixel data D(i) obtained in the dark measurement from the pixel data D(i) obtained by the sampling measurement in order to remove the dark current noise. And the spectral radiance is calculated from the calculation result.

If the spectral radiance is measured in such a manner, the saturation of the photodiode 128 does not occur, and the light to be measured 604 whose amount of light periodically changes can be appropriately measured in a short time. Further, the spectroradiometer 1 is also provided with the advantage that the dimming filter 104 having an extremely low transmittance which is difficult to ensure the accuracy of the transmittance is not required in order to prevent saturation of the electric charge.

In addition, although the number M of divisions of the measurement period MP may be determined in advance, and M times of the accumulation time determined in step S102 is used as the measurement time, the accumulation time determined in step S102 may be used. The operation unit 118 receives the input measurement time to determine the division number M of the measurement period MP. If this is the case, the measurement time can be made constant without being affected by the accumulation time, and when the amount of light to be measured 604 is large, it is likely to be affected by flicker, and the number of divisions M is increased. On the other hand, when the amount of light to be measured 604 is small and is not easily affected by flicker, the number of divisions M is small, and therefore the amount of light to be measured 604 can be appropriately measured.

〈

Fig. 6 is a view showing an example of the measurement results of the spectral radiance luminance meter of the prior art and the spectroradiometer 1 of the first embodiment of the present invention. In Fig. 6, for each of the light to be measured whose frequency of variation is 20 to 200 Hz, the spectroradiometer 1 of the first embodiment of the present invention and the spectroradiometer 1 of the first embodiment of the present invention are shown. The maximum value, the minimum value, the average value, and the error range of the reading of the brightness when the brightness is measured. Here, the measurement time was set to 1/60 second.

As is clear from Fig. 6, the measurement result by the spectroradiometer 1 of the first embodiment can be well repeated in a wider range of frequencies than the prior art spectroradiometer. Accuracy.

<2 Second Embodiment>

Fig. 7 is a schematic view showing a luminance meter 2 according to a second embodiment of the present invention. The luminance meter 2 mainly measures the brightness of the light to be measured 604 by using the light emitted from the display 602 such as a CRT display, a plasma display, or a liquid crystal display as the light to be measured 604.

As shown in FIG. 7 , the luminance meter 2 includes an optical system 202 , an aperture 204 , a shutter 206 , a sensor 210 , an A/D converter 212 , a communication interface 214 , a display unit 216 , and an operation unit 218 . The synchronization signal input terminal 220 and the control calculation unit 222.

The optical system 202 guides the light to be measured 604 incident on the luminance meter 2 to the sensor 210. The optical system 202 can be constructed by combining a lens or a mirror.

The aperture 204 limits the beam of light transmitted through it. The aperture 204 is opened and closed under the control of the control calculation unit 222. When the aperture 204 is closed, the light incident on the luminance meter 2 is limited by the aperture 204 and reaches the sensor 210. On the other hand, when the aperture 204 is turned on, the light to be measured 604 incident on the luminance meter 2 is not limited and reaches the sensor 210. Therefore, the aperture 204 functions as an adjustment means for adjusting the amount of light of the light to be measured 604 at the sensor 210.

The shutter 206 shields the light. The shutter 206 is controlled by the control calculation unit 222, and is inserted and removed in the optical path of the light to be measured 604. When the shutter 206 is inserted into the optical path of the light to be measured 604, the light to be measured 604 incident on the luminance meter 2 does not reach the sensor 210. On the other hand, when the shutter 206 is removed from the optical path of the light to be measured 604, the light to be measured 604 incident on the luminance meter 2 reaches the sensor 210.

The sensor 210 receives the light-measured light 604 and outputs a signal representing the amount of light of the light to be measured 604.

FIG. 8 is a circuit diagram of the sensor 210. As shown in FIG. 8 , the sensor 210 is provided with a photodiode 240 , a differential amplifier 242 , a non-inverting amplifier 244 , capacitors 246 , 248 , 250 , switch 252 , 254 , and a discharge switch 256 . 258, 260.

At the input of the differential amplifier 242, an optical diode 240 is connected, and at the output of the differential amplifier 242, capacitors 246, 248 are connected via a changeover switch 252. The differential amplifier 242 amplifies and outputs the signal output from the photodiode 240. The changeover switch 252 is controlled by the control calculation unit 222 to switch the output of the differential amplifier 242 between the capacitor 246 and the capacitor 248. More specifically, the changeover switch 252 connects the output of the differential amplifier 242 to the capacitor 246 in the odd-numbered accumulation periods SP(1), SP(3), ..., and stores the even number of times. During the period SP(2), SP(4), ..., the output of the differential amplifier 242 is connected to the capacitor 248. Thereby, the signal output from the photodiode 240 is amplified by the differential amplifier 242, and the amplified signal is generated in the odd-numbered accumulation periods SP(1), SP(3), . It is applied to the capacitor 246, and the amplified signal is applied to the capacitor 248 in the even-numbered accumulation periods SP(2), SP(4), . As a result, in the odd-numbered accumulation periods SP(1), SP(3), ..., the electric charge corresponding to the amount of light received by the photodiode 240 is accumulated in the capacitor 246, and the even-numbered accumulation is accumulated. In the periods SP(2), SP(4), ..., the electric charge corresponding to the amount of light received by the photodiode 240 is accumulated in the capacitor 248.

At the input of the non-inverting amplifier 244, capacitors 246, 248 are coupled via switch 254, and at the output of non-inverting amplifier 244, capacitor 250 is coupled. The voltage amplification factor of the non-inverting amplifier 244 is 1, and the input impedance of the non-inverting amplifier 244 is sufficiently high. The changeover switch 254 is controlled by the control calculation unit 222, and the connection destination of the input of the non-inverting amplifier 244 is switched between the capacitor 246 and the capacitor 248. More specifically, the changeover switch 254 connects the input of the non-inverting amplifier 244 to the capacitor 246 after the end of the odd-numbered accumulation periods SP(1), SP(3), ..., and is in the even number After the end of the accumulation period SP(2), SP(4), ..., the input of the non-inverting amplifier 244 is connected to the capacitor 248. As a result, after the end of the odd-numbered accumulation periods SP(1), SP(3), ..., the voltage at the both ends of the capacitor 246 is applied to the capacitor 250 at the same number. After the end of the accumulation period SP (2), SP (4), ..., a voltage equal to the voltage across the capacitor 248 is applied to the capacitor 250. As a result, after the end of the odd-numbered accumulation periods SP(1), SP(3), ..., the amount of charge accumulated in the capacitor 250 is the same as the amount of charge accumulated in the capacitor 246. After the end of the even number of accumulation periods SP (2), SP (4), ..., the electric charge accumulated in the capacitor 250 is the same as the electric charge accumulated in the capacitor 248. That is, it is possible to obtain the same result as the transfer of the charge accumulated in the capacitor 246 or the capacitor 248 to the capacitor 250.

The voltage across the capacitor 250 is output to the A/D converter 212 as an output of the sensor 210.

Capacitors 246, 248, 250 are connected in parallel to discharge switches 256, 258, 260, respectively. The discharge switches 256, 258, and 260 are controlled to open and close by the control unit, and discharge the electric charges accumulated in the capacitors 246, 248, and 250, respectively. Specifically, the discharge switches 256 and 258 respectively discharge the charges accumulated in the capacitors 246 and 248 after the charges accumulated in the capacitors 246 and 248 are transferred to the capacitor 250, and the discharge switch 260 is discharged. After the voltage generated by the accumulation of the electric charge to the capacitor 250 is output as the output of the sensor 210, the electric charge accumulated in the capacitor 250 is discharged.

In this manner, between the capacitor 246 and the capacitor 248, the even-numbered accumulation periods SP(1), SP(3), ... and the even-numbered accumulation periods SP(2), SP(4) In the period until the next accumulation period comes, the charge accumulated in the capacitor 246 or the capacitor 248 is transferred to the other capacitor 250 while the storage means for accumulating the charge generated in the ... is switched. At the same time, the electric charge is stored, and the electric charge accumulated in the middle of the measurement period MP is transmitted and A/D-converted.

If it is returned to FIG. 7 and described, the A/D converter 212 converts the analog signal output from the sensor 210 into digital data and outputs it to the control calculation unit 222. Thereby, the A/D converter 212 can convert the amount of electric charge accumulated in the capacitor 250 into a digital value and output it.

The communication interface 214 connects the luminance meter 2 to an external device such as an external computer.

The display unit 216 displays the measurement result of the luminance meter 2.

The operation unit 218 is an operator who receives an fluctuation period of the amount of light to be measured or an input of the measurement time.

The synchronizing signal input terminal 220 obtains a signal in which a vertical synchronizing signal generally changes in synchronization with a change in the amount of light of the light to be measured 604 as in the case of measuring light emitted from the CRT display.

The control calculation unit 222 is an embedded computer including at least a CPU 236 and a memory 238, and causes the CPU 236 to execute a control program read from the memory 238 to face the aperture 204, the shutter 206, and the sensor 210. The A/D converter 212, the communication interface 214, the display unit 216, the operation unit 218, or other units of the luminance meter 2 are controlled. Further, the control calculation unit 222 calculates the brightness from the digital data acquired from the A/D converter 212 by causing the CPU 236 to execute the control program read from the memory 238.

The control calculation unit 222 transmits the charges accumulated in the capacitors 246 and 248 from the capacitors 246 and 248 at the sensor 210 while the photodiode 240 is performing the photoelectric conversion of the measurement light 604. To the capacitor 250, an analog signal having a voltage corresponding to the amount of the transferred charge is output, and in the A/D converter 212, the analog signal output from the sensor 210 is converted into a digital position. data.

As a result, the electric charge generated by the photodiode 240 during the measurement period and accumulated in the capacitors 246 and 248 is read and divided into a plurality of times, and the control unit 222 is obtained as shown in FIG. The plurality of accumulation periods SP(1), SP(2), ..., SP(M) after the division of the measurement period MP are generated by the photodiode 240 and accumulated in the capacitors 246, 248. The digital data d(1), d(2), ..., d(M) of the amount of charge q(1), q(2), ..., q(M). Here, the digital data d(j) is generated and stored in the capacitors 246 and 248 in response to the photodiode 240 in the accumulation period SP(j) (j=1, 2, ..., M). The analog signal a(j) of the voltage of the amount of charge q(j) is converted into a digital value.

Further, the control calculation unit 222 accumulates the plural pixel data d(1), d(2), ..., d(M) according to Equation 2, and calculates that the sensor 210 is in the measurement period MP in response to the measurement. The digital data d(1), d(2), ..., d(N) of the generated and accumulated amounts of charge q(1), q(2), ..., q(N).

In the same manner as the spectroradiometer 1 of the first embodiment, the luminance meter 2 can prevent the saturation of the photodiode 240 and periodically change the amount of light in a short time. The measured light 604 is measured.

(3 other)

In the first embodiment described above, an example in which the present invention is applied to the spectroradiometer 1 for measuring the spectral radiance of the light to be measured 604 is described. In the second embodiment, The luminance meter 2 for measuring the brightness of the light to be measured 604 is described by applying the example of the present invention, but the scope of application of the present invention is not limited thereto. In other words, the present invention can be applied to various light amount measuring devices that measure the amount of light of the light to be measured 604, such as an illuminometer or a spectrophotometer.

Further, in the above description, in all cases, the description is merely illustrative, and the present invention is not limited thereto. It is to be understood that numerous modifications, not exemplified, can be devised without departing from the scope of the invention. In particular, it is needless to say that the technique described in the first embodiment can be combined with the technique described in the second embodiment.

1. . . Spectroradiometer

2. . . Luminance meter

104. . . Dimming filter

110, 210. . . Sensor

112, 212. . . A/D converter

122, 222. . . Control calculation department

118,218. . . Operation department

120, 220. . . Synchronous signal input terminal

128, 240. . . Light diode

246, 248. . . Capacitor

Fig. 1 is a schematic view showing a spectroradiometer according to the first embodiment.

Figure 2 is a plan view of the sensor.

Figure 3 is a graph showing the relationship between the measurement period and the accumulation period.

Fig. 4 is a flow chart for explaining the operation of the spectroradiometer.

Fig. 5 is a flow chart for explaining the operation of the spectroradiometer.

Fig. 6 is a view showing an example of the measurement result.

Fig. 7 is a schematic view showing a luminance meter of the second embodiment.

Figure 8 is a circuit diagram of the sensor.

1. . . Spectroradiometer

102. . . Optical system

104. . . Dimming filter

106. . . Shutter

108. . . Dispersing element

110. . . Sensor

112. . . A/D converter

114. . . Communication interface

116. . . Display department

118. . . Operation department

120. . . Synchronous signal input terminal

122. . . Control calculation department

136. . . CPU

138. . . Memory

602. . . monitor

604. . . Measured light

Claims (7)

A light amount measuring device is a light amount measuring device that measures the amount of light to be measured, and is characterized in that: a charge generating means is provided, and a charge corresponding to the amount of light of the light to be received is received; and a storage means is provided. And accumulating the electric charge generated by the electric charge generating means; and the A/D converting means converting the amount of electric charge accumulated in the accumulating means into a digital value; and accumulating means accumulating the plural digital value And the control means for controlling the light quantity measuring device by the control means, wherein the charge generating means adjusts the amount of light corresponding to the amount of light of the light to be received during the measurement period. In the meantime, the accumulation means is continued, and the charge means generates the charge generated by the charge generation means in each of the accumulation periods in which the plurality of divisions are performed without interruption during the measurement, and the A/D conversion is performed. The means is stored in each of the plurality of accumulation periods during the period in which the electric charge generated by the electric charge generating means is received. The amount of charge in said accumulator means for converting the bit number value, the accumulation means, the digital system the A / D converting means for converting the complex of the accumulated value for. The light quantity measuring device according to the first aspect of the invention, further comprising: adjusting means, based on the opening during the measuring period Before the start, the amount of light to be measured is measured in advance, and the amount of light to be measured at the charge generating means is adjusted. The light quantity measuring device according to the first or second aspect of the invention, wherein the control means determines the storage period based on the amount of light to be measured which is previously measured before the start of the measurement period. length. The light quantity measuring device according to the first aspect of the invention, wherein the control means determines the length of the accumulation period based on a fluctuation period of the amount of light to be measured. The light quantity measuring device according to the fourth aspect of the invention, further comprising: a first receiving means for receiving an input of a fluctuation period of the amount of light to be measured, wherein the control means is based on the first The length of the accumulation period is determined by the period of change accepted by the input means. The light quantity measuring device according to the fourth aspect of the invention, further comprising: obtaining means for obtaining a signal that changes in synchronization with a change in the amount of light to be measured, wherein the control means is obtained by the obtaining The signal obtained by the means detects the fluctuation period of the amount of light to be measured, and determines the length of the accumulation period based on the detected fluctuation period. The light quantity measuring device according to the first aspect of the invention, further comprising: a second receiving means for receiving an input of a length of the measurement period, wherein the control means is based on a length of the accumulation period and the length 2 The number of divisions during the measurement period is determined by the length of the measurement time accepted by the means.